Balloon catheters have heretofore been used for treatment of stenoses due to thrombi formed in organic lumina of blood vessels, bile ducts, air tubes and other organs.
A balloon catheter has a form approximately as shown in FIG. 1, and having a guide wire (GW) inserted through its internal cavity from a guide wire port 11, where the guide wire (GW) is inserted into, for example, a blood vessel. A balloon catheter (BC) is required to have an ability to cross to an objective area (cross ability), and therefore, is required to have an ability to be pushed into an objective area along the guide wire (GW) (pushability), followability which allows the balloon catheter (BC) to be easily deformed along the guide wire (GW), and a lubricative property of a portion to be inserted. To improve the pushability and the followability, a shaft 1 of the balloon catheter (BC) in general is flexible in a distal section 12 on a distal side relative to the guide wire port 11 and is stiff on a proximal side relative to the same. In addition, to improve the cross ability, a lubricative property is imparted by lubrication processing to the distal section 12 on the distal side relative to the guide wire port 11, which section includes the balloon 3 and a distal portion 2 extending from the balloon straight portion toward the distal end. As a method for lubrication processing, in general, the formation of a lubricant film by silicone coating or hydrophilization processing with polyvinylpyrrolidone (PVP) or the like is adopted (U.S. Pat. Nos. 5,503,631 and U.S. Pat. No. 6,306,144). In FIG. 1, reference numeral 36 denotes a marker for confirming the position of the inserted balloon 3.
There is a case where stenoses occur in both bifurcated blood vessels in the vicinity of, for example, a bifurcation of a blood vessel. In this case, as shown in FIG. 4, two balloon catheters (BC and BC) are respectively inserted into areas which extend from the bifurcation to the bifurcated blood vessels, and balloons (B and B) are respectively expanded to perform treatment for expanding the stenoses (U.S. Pat. No. 4,896,670).
However, the operation (kissing techniques) of introducing two balloon catheters into a bifurcation of a blood vessel and inserting and expanding their respective balloons in areas which extend from the bifurcation to the bifurcated blood vessels has the problem that when the balloons are expanded, the mutually adjacent balloons slip together and one of the balloons moves and deviates from the objective area (see, FIGS. 5b: one slips toward the distal end, and 5c: one slips toward the proximal end) so that the balloon that has deviated from the objective area cannot accurately expand the stenosis (see, FIGS. 5a, 5b and 5c).
The present invention has been made in view of the above-mentioned problem, and an object of the invention is to provide a balloon catheter which is improved in cross ability and is also improved in stability in an objective area (gripping property), which properties are adjusted with good balance so as not to cause slipping during kissing techniques.